Workpiece grinder with lead generating capability

ABSTRACT

A machine having a drive motor which rotates a tapered workpiece having peripheral cutting spirals through constant velocity universal joints and which simultaneously moves the workpiece longitudinally to generate a lead which corresponds to the lead of the cutting spirals. The machine has an upper table which can be horizontally tilted to compensate for the taper of the workpiece so that a rotating grinder wheel, fixed in a predetermined vertical position above the workpiece, frictionally engages and grinds each cutting spiral as the workpiece is driven. A lead start selector permits workpiece to be turned relative to the grinder wheel before a grinding operation so that the start of any cutting spiral is engaged by the grinding wheel.

llnited States Patent [191 McCord et a1.

[ 1 Sept. 2, 11975 WORKPIECE GRINDER WITH LEAD GENERATING (IAPABILITY[75] Inventors: Douglas M. McCord, Grand Blanc;

Victor .1. Laing; Darrell D. Diem, both of Flint, all of Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

22 Filed: Mar. 28, 1974 21 Appl. No.: 455,543

Primary ExaminerAl Lawrence Smith Assistanl Examiner-Nicholas P. GodiciAttorney, Agent, or FirmCh;ar1es R. White 5 7 ABSTRACT A machine havinga drive motor which rotates a ta pered workpiece having peripheralcutting spirals through constant velocity universal joints and whichsimultaneously moves the workpiece longitudinally to generate a leadwhich corresponds to the lead of the cutting spirals. The machine has anupper table which can be horizontally tilted to compensate for the taperof the workpiece so that a rotating grinder wheel, fixed in apredetermined vertical position above the workpiece, frictionallyengages and grinds each cutting spiral as the workpiece is. driven. Alead start selector permits workpiece to be turned relative to thegrinder wheel before a grinding operation so that the start of anycutting spiral is engaged by the grinding wheel.

3 Claims, 4 Drawing Figures PATENTED SEP 21975 WORKPIECE GRINDER WITHLEAD GENERATING CAPABILITY This invention relates to workpiece grindersand more particularly to a machine for grinding the cutting spirals oftapered workpieces in which the workpiece can be adjusted topredetermined horizontal positions, rotated and longitudinally traversedto generate the lead of the cutting spirals to permit a rotatinggrinding wheel fixed in vertical position to sharpen the cuttingspirals.

The preferred embodiment of this machine has a fixed base which supportsa longitudinally movable lower table. An upper table, carried by thelower table, can be tilted relative to the lower table to place atapered cylindrical workpiece supported on the upper table in a positionto effectively eliminate the workpiece taper to facilitate grinding ofthe workpiece. A rotatable grinding wheel fixed at a vertical stationfrictionally engages a cutting spiral of the workpiece as the workpieceis rotated and moved longitudinally by speed controlled powertransmission means that generates a lead which corresponds to the leadof the cutting spiral. The workpiece is held on the upper table byheadstock and tailstock means. The headstock carries adjustable leadstart selector means which permits the rotational adjustment of theworkpiece so that cutting spirals intermediate of a first spiral andhaving spaced starts can be effectively matched with the grinding wheelfor subsequent grinding operations.

The machine has a gear box fixed to the stationary base which supports ahydraulic motor. This motor drives a gear train which is drivinglyconnected to a rotatable shaft in the head stock through constantvelocity universal joint means allowing the rotatable shaft and theworkpiece to be driven at a constant velocity and further allowing theupper table to be tilted relative to the lower table. The rotatableshaft in the head stock is connected to the lead start selector byindexing means which permits the adjustment of the lead start selectorrelative to the rotatable shaft so that the start of different spiralsof the workpiece can be matched with the grinding wheel. The gear trainfurther drives a lead screw that extends through a ball nut that isconnected to the lower table to provide for the traversing of the lowertable, the upper table, the headstock, the tailstock. and the workpiececarried thereby. With this construction the workpiece will be movedlongitudinally as it is turned so that the lead of the spiral isgenerated by the machine. The gearing in the gear box can be readilychanged to change the lead generated and provide for the grinding ofworkpieces having different leads. I

These and other features, objects and advantages of the invention willbe more apparent from the following detailed description and drawing inwhich:

FIG. I is a side view of a preferred embodiment of the invention;

FIG. 2 is a view taken generally along lines 2--2 of FIG. 1 with someparts being shown in cross section;

FIG. 3 is a view taken generally along lines 33 of FIG. 2 and FIG. 4 isa fragmentary view taken generally along lines 4-4 of FIG. 2.

Turning now to the drawings there is shown in FIG. I a workpiecegrinding machine having a stationary base on which there is mounted alongitudinally movable lower table 12. This movement is provided byconventional T-slots in the top surface of the base 10 which receivecooperating slides projecting from the lower table 12. The lower table12 has an upstanding support 16 fixed near one end thereof whichreceives a pivot pin 18 secured to an upper table 20. The lower tablealso has an adjustment screw 22 threaded therein adjacent to the otherend formed with a rounded tip 23 which bears against the lower-surfaceof the upper table. A handle 24 fixed to the adjustment screw is used tomanually turn the adjustment screw to pivot the upper table a limitedextent about pivot pin 18 and thereby tilt the upper table with respectto the lower table. After being tilted a sufficient amount, a Jo block26 is positioned between a support pad 28, fixed to the lower table 12,and a sine bar 30 fixed to the upper table 20. After the .10 block isinstalled in position, the adjustment screw 22 is retracted into thelower table so that the sine bar rests on the Jo block to provide aprecise and predetermined inclination of the upper table with respect tothe lower table to position the tapered workpiece 32, supported by theupper table 20, in a horizontal position to compensate for the taperangle of the workpiece.

The machine has a headstock 34 which is adjustably mounted inlongitudinally extending T slots, not shown, in the top of upper table20 and which is secured in adjusted position by locking screw means 36.A rotatable drive shaft 38, journaled in the headstock, has a projectingend on which a thread lead start selector 42 is rotatably mounted. Therotatable drive shaft 38 further has a disc-like front plate 44 fixedthereto adjacent to the thread lead start selector 42 which carries anindexing plunger 46.

The indexing plunger 46 has a movable projecting finger portion 47 whichextends through the front plate and is removably engageable with any oneof a circular series of equally spaced holes 48 drilled into theadjacent end surface of the lead start selector. When so engaged thelead start selector is drivingly secured to the rotatable front plate44. By axially withdrawing the finger portion from one of the openings48, the lead start selecter can be rotated relative to the front plate44 to predetermined adjusted positions and again connected with thefront plate 44 by extending finger 45 into an aligned opening 48. Aswill be later described this procedure is used to rotate the workpiece32 so that the spaced lead starts of different cutting spirals of theworkpiece can be engaged by a grinding tool.

The front face of the lead start selector 42 has a pair of lugs 47secured thereto which receive threaded adjustment screws 49. Thesescrews adjustably secure a driver 50 to the lead start selector 42 sothat the lead start selector can be rotated relative to the front platethe driver. The workpiece in the drawing is a spiraled broach which ismounted between aligned centers 52 and 54 extending longitudinally fromthe lead start selector 34 and from a tailstock 56 adjustably mounted inthe T slots in the top of the table 20. Screw locking means 58 isemployed to secure the tailstock in ad justed position. The headstock 34and tailstock 56 are advanced or retracted with respect to each other toaccommodate workpieces of varying lengths. The tail stock has a handwheel 60 connected to the center 54 by a shaft threaded through thetailstock which is turned clockwise or counterclockwise to accordinglyadvance or retract the center 54 to facilitate loading and unloading ofbroaches into the machine.

As shown, the broach 32 has a stem 62 which extends through a centralyoke 64 of the driver and is locked thereto by a screw 66 which isthreaded through the yoke into engagement with the stem 62. The broachcan have one or more leads, for example broach 32 can have separatecutting spirals 68, 70 and 72. These spirals have starts spaced 120apart spiraling around the periphery of the broach from the larger endto the smaller end. The three separate cutting spirals are sharpened bya grinding assembly 74 which has a housing 76 pivotally mounted on astationary column 78 that may be fixed to the base 10. As shown, thegrinding assembly 74 has a powered rotatable grinding wheel 80 that ispositioned by turning the housing to a predetermined fixed station inwhich the grinding wheel is in grinding contact with the front face of aselected one of the three cutting spirals.

To rotate and traverse the spiral broach, a hydraulically operated powertransmission is employed. As shown in FIG. 1, there is a hydraulic motor84, fixed to a gear box 86, which drives a spur gear 88. Spur gear 88meshes with a second spur gear 90 which is drivingly connected to aconstant velocity universal joint 92 disposed adjacent to one side ofthe gear box. Universal joint 92 is drivingly connected to a shaft 94which is in turn drivingly connected to a second constant velocityuniversal joint 96 that is supported by a steady rest 98 secured to thegear box. The second universal joint is drivingly connected to arotatably splined shaft 100 that extends longitudinally through theheadstock and into a longitudinally extending tubular cover 102 which issupported at one end by a plate 103 fastened to the headstock and at theother end by a support 104 fixed to table 20. The headstock 34 has aspur gear 106 which is slidably mounted on and is rotatably driven bythe splined shaft 100. This spur gear meshes with a second spur gear 108which drives shaft 38 that extends through the headstock and which isdrivingly connected with front plate 44. Thus, when the index plunger 46is engaged with one of the holes 48 in the lead start selector and theconnected spiral broach 32 will be rotatably driven at a constantvelocity by the motor 84.

The hydraulic motor 84 also supplies the power to longitudinally movethe spiral broach 32 as it is being rotated. As shown. the spur gear 90is connected to a larger spur gear 107 which drives a gear traincomprising meshing gears 109, 110 and 112. Spur gear 112 rotatablydrives a lead screw 114 which extends through a passage in the lowertable 10 and is rotatably journaled in a lead screw support 116 locatedat the far end of the base. A ball nut 118, mounted on the lead screw.is connected to the lower table by a bracket 120 so that rotation of thelead screw moves the lower table and the connected upper tablelongitudinally with respect to base 10. Since the headstock andtailstock are fixed to the upper table these components will be movedalong with the upper table and the broach is thus moved longitudinallyas it is being rotated.

Suitable controls, not shown, for the hydraulic motor 84 are employed tocontrol the speed and direction of rotation of motor 84.

The constant velocity universal joints permit the tilt adjustment of theupper table relative to the base so that the tapered workpiece can bepositioned at a selected angle to compensate for the angle of taper..Also, these universal joints provide for the rotation drive of theworkpiece at a constant angular velocity. This important feature permitsthe turning speed of the workpiece to be corrolated with the traversingspeed of the workpiece. For example if the spirals 68, 70 and 72 have aone inch lead, the workpiece must be longitudinally traversed one inchfor each revolution. This is accomplished by the appropriate selecton ofgearing for the gear train. If the rotation of shaft 114 produces a 1inch longitudinal movement of the tables the gearing should be selectedso that shafts 100 and 114 are driven at the same speed. For other leadsappropriate gearing may be readily substituted for the gearing in gearbox 86.

To prepare the machine for a grinding operation the headstock andtailstock are set a predetermined distance from each other toaccommodate the length of a workpiece such as the tapered spiral broach32. The broach 32 is placed in the machine with the stem 62 insertedthrough the driver yoke 64 and in engagement with the center 52. Wheel60 is turned to advance the center 54 of the tailstock into engagementwith the other end of the broach 32. Driver screw 66 is advanced in theyoke to rigidly secure the broach to the driver. After the broach isloaded, the upper table is tilted and a selected Jo block 26 isinstalled to fix the angle of inclination of the upper table 20 to equalthe taper of the broach. This adjustment makes the top line or uppersurface of the broach parallel to the machine base 10. After the uppertable is inclined, the upper and lower tables are longitudinally movedto locate the portion of the broach requirihg sharpening adjacent to thegrinding wheel assembly 74. During this movement the housing 76 andconnected grinding wheel 80 have been turned to an out-of-the-wayposition. For example, the broach is moved longitudinally to the rightuntil the grinding wheel 80 is adjacent to the larger diameter end ofthe broach. The lead start selector is turned until the start of aselected spiral 68 is properly aligned with the grinding wheel 80 whenit has been turned into a working position such as shown in FIG. 1.Screws 49 can be used as a fine adjustment for turning the workpiece 32.After this setup, the motor 84 is activated to turn the broach 32counterclockwise as it is being moved leftwardly. With the grinder wheel80 rotatably driven and with the broach turning as it is beinglongitudinally traversed, the grinder wheel will grind the spiral 68 tosharpen this spiral from one end to the other. In the event that only aportion of the spline need be sharpened the machine setup can be suchthat only the portion of the broach that needs to be ground is worked onby the grinding wheel. In a similar manner the other spiral splines 70and 72 are ground. After the broach has been ground, the grinderassembly 74 is turned to its out-of-the-way position and the broach isremoved from the machine.

While a preferred construction has been shown and described for purposesof illustrating this invention, the scope of the invention is set forthby the following claims.

We claim:

1. A grinder for a workpiece comprising a stationary base, first tablemeans mounted for longitudinal movement on said base, second tablemeans, pivot means mounting said second table means on said first tablemeans for limited tilting movement about a horizontal axis, tailstockmeans mounted on said second table means, lead start selector meansrotatably mounted on said second table spaced from said tailstock means,said workpiece being elongated and tapered and having cutting spiralmeans disposed around the periphery thereof, said workpiece having anend portion secured to said lead start selector means and another endportion supported by said tailstock means, rotatable spiral grindermeans positioned at a predetermined station adjacent to said workpiece,means to tilt said second table means with respect to said first tablemeans at an angle equal to the taper angle of said workpiece, motormeans for simultaneously rotating and traversing said workpiece relativeto said grinder means, first power transmission means operativelyconnecting said motor means to said lead start selector means to drivesaid lead start selector means and said workpiece at a constant angularvelocity, second power transmission means operatively connecting saidmotor means to said second table means for longitudinally moving saidsecond table means and said workpiece at a predetermined speed tothereby generate a lead equal to the lead of said cutting spiral meansso that said grinder means can effectively grind said cutting spiralmeans.

2. A grinder for a workpiece comprising a stationary base, first tablemeans mounted for longitudinal sliding movement on said base, secondtable means, horizontal pivot means mounting said second table means onsaid first table means for limited tilting movement with respect topivot means, spaced headstock and tailstock means mounted on said secondtable means, lead start selector means, said workpiece being elongatedand tapered and having cutting spiral means disposed around theperiphery thereof, said workpiece having an end portion secured to saidlead start selector means and another end portion supported by saidtailstock means, rotatable spiral grinder means positioned at apredetermined station adjacent to said workpiece, gauge means to tiltand fix said second table means with respect to said first table meansat an angle equal to the taper angle of said workpiece, motor meansfixed with respect to said base for simultaneously rotating andtraversing said workpiece relative to said grinder means, first powertransmission means operatively connecting said motor means to said leadstart selector means, said first power transmission means having firstand second constant velocity universal joints operatively connectingsaid lead start selector means to said motor means to permit said secondtable means to be tilted relative to said first table means and to drivesaid lead start selector means and said workpiece at a constant angularvelocity, indexing means for adjustably securing said lead startselector means to said first power transmis sion means, second powertransmission means operatively connecting said motor means to saidsecond table means for longitudinally moving said second table means andsaid workpiece at a predetermined speed to thereby generate a lead equalto the lead of said cutting spiral means so that said grinder means caneffectively grind said cutting spiral means.

3. A lead generating grinder for a tapered workpiece having a pluralityof cutting spirals with spaced lead starts comprising a stationary base,first table means, slide means mounting said first table means forlongitudinal movement along said base, second table means, pivot meanspivotally mounting said second table means on said first table means,headstock means mounted on said second table for continuous rotationabout a longitudinal axis, tailstock means, means adjustably mountingsaid tailstock means on said second table at a spaced and predetermineddistance from said headstock means, lead start selector means supportedby said headstock means for rotation therewith, index means foradjustably securing said lead start selector means at different selectedpositions with respect to said headstock means, said workpiece having anaxis coinciding with said longitudinal axis and having one end thereofrotatably supported in said tailstock means and the opposite end thereoffastened to said rotatable lead start selector means, rotatable grindermeans positioned at a predetermined station adjacent to said workpiece,means to adjust the angle of said second table with respect to said baseso that the upper surface of said tapered workpiece is parallel to saidbase, a motor, power transmission means; operatively connecting saidmotor to said headstock means and to said first table means to permitsaid motor to simultaneously rotate said headstock means andlongitudinally move said tables to thereby simultaneously rotate andlongitudinally move said workpiece to permit said grinder means to grindthe spirals of said workpiece beginning with the lead starts thereof,and indexing means for adjustably securing said lead start selectormeans at different rotary positions with respect to said headstock meansso that said grinder means can be positioned to grind the spacedlead-starts of each of the spirals of said UNITED STATES PATENT ANDTRADEMARK OFFICE QER'TTFICATE OF CORRECTION PATENT NO. 3, 902,281

DATE September 2, 1975 INV ENTOR( I Douglas M. McCord et al It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 53, "be rotated relative to the front plate" should becan rotate the workpiece 32 connected to line 43, "selecter" should beselector Column 4, line 7, "selecton" should be selection Signed andsealed this thirteenth Day Of April 1976 [SEAL] A ttes I:

RUTH C. MASON Arresting Officer C. MARSHALL DANN (mnnu'ssimu'ruj'lau'r'zrs and Trademarks

1. A grinder for a workpiece comprising a stationary base, first tablemeans mounted for longitudinal movement on said base, second tablemeans, pivot means mounting said second table means on said first tablemeans for limited tilting movement about a horizontal axis, tailstockmeans mounted on said second table means, lead start selector meansrotatably mounted on said second table spaced from said tailstock means,said workpiece being elongated and tapered and having cutting spiralmeans disposed around the periphery thereof, said workpiece having anend portion secured to said lead start selector means and another endportion supported by said tailstock means, rotatable spiral grindermeans positioned at a predetermined station adjacent to said workpiece,means to tilt said second table means with respect to said first tablemeans at an angle equal to the taper angle of said workpiece, motormeans for simultaneously rotating and traversing said workpiece relativeto said grinder means, first power transmission means operativelyconnecting said motor means to said lead start selector means to drivesaid lead starT selector means and said workpiece at a constant angularvelocity, second power transmission means operatively connecting saidmotor means to said second table means for longitudinally moving saidsecond table means and said workpiece at a predetermined speed tothereby generate a lead equal to the lead of said cutting spiral meansso that said grinder means can effectively grind said cutting spiralmeans.
 2. A grinder for a workpiece comprising a stationary base, firsttable means mounted for longitudinal sliding movement on said base,second table means, horizontal pivot means mounting said second tablemeans on said first table means for limited tilting movement withrespect to pivot means, spaced headstock and tailstock means mounted onsaid second table means, lead start selector means, said workpiece beingelongated and tapered and having cutting spiral means disposed aroundthe periphery thereof, said workpiece having an end portion secured tosaid lead start selector means and another end portion supported by saidtailstock means, rotatable spiral grinder means positioned at apredetermined station adjacent to said workpiece, gauge means to tiltand fix said second table means with respect to said first table meansat an angle equal to the taper angle of said workpiece, motor meansfixed with respect to said base for simultaneously rotating andtraversing said workpiece relative to said grinder means, first powertransmission means operatively connecting said motor means to said leadstart selector means, said first power transmission means having firstand second constant velocity universal joints operatively connectingsaid lead start selector means to said motor means to permit said secondtable means to be tilted relative to said first table means and to drivesaid lead start selector means and said workpiece at a constant angularvelocity, indexing means for adjustably securing said lead startselector means to said first power transmission means, second powertransmission means operatively connecting said motor means to saidsecond table means for longitudinally moving said second table means andsaid workpiece at a predetermined speed to thereby generate a lead equalto the lead of said cutting spiral means so that said grinder means caneffectively grind said cutting spiral means.
 3. A lead generatinggrinder for a tapered workpiece having a plurality of cutting spiralswith spaced lead starts comprising a stationary base, first table means,slide means mounting said first table means for longitudinal movementalong said base, second table means, pivot means pivotally mounting saidsecond table means on said first table means, headstock means mounted onsaid second table for continuous rotation about a longitudinal axis,tailstock means, means adjustably mounting said tailstock means on saidsecond table at a spaced and predetermined distance from said headstockmeans, lead start selector means supported by said headstock means forrotation therewith, index means for adjustably securing said lead startselector means at different selected positions with respect to saidheadstock means, said workpiece having an axis coinciding with saidlongitudinal axis and having one end thereof rotatably supported in saidtailstock means and the opposite end thereof fastened to said rotatablelead start selector means, rotatable grinder means positioned at apredetermined station adjacent to said workpiece, means to adjust theangle of said second table with respect to said base so that the uppersurface of said tapered workpiece is parallel to said base, a motor,power transmission means operatively connecting said motor to saidheadstock means and to said first table means to permit said motor tosimultaneously rotate said headstock means and longitudinally move saidtables to thereby simultaneously rotate and longitudinally move saidworkpiece to permit said grinder means to grind the spirals of saidworkpiece beginning with the lead starts thereof, and indexing means foRadjustably securing said lead start selector means at different rotarypositions with respect to said headstock means so that said grindermeans can be positioned to grind the spaced lead starts of each of thespirals of said workpiece.